Reverse drilling rock bit



July 10, 1962 'c. M. BOYLE REVERSE DRILLING ROCK BIT Filed March 13, 1958 INVENTOR,

C. M. B OY L E BY 3,043,385 REVERSE DRILLING RGCK BIT Charles Morris Boyle, Kimball, Nebr. (Box 6086, Hannigen Station, St. Louis 10, Mo.) Filed Mar. 13, 1958, Ser. No. 721,262 1 Claim. (Cl. 175-401) This invention relates to rock drill bits and more particularly it is an object of this invention to provide an improved bit for more easy and speedy withdrawal from the drill hole.

In many rock formations the drill hits small rocks or water seams. It is not always noticeable to the driller until he starts to remove the drill steel. The dry chips formed by deeper drilling collect at the moist seams and make the drill hole smaller. Then when the driller starts to remove the drill steel, the bit hits the moist seam and compresses the rock dust, mud and water at the upper edge of the outwardly flared bottom portion of the conventional bell shaped rock bit. This causes the drill steel to stick.

Often there is no solution for drill steel that is stuck but to abandon it and drill a new hole. This has a high cost, especially when it is considered that this is not an uncommon occurrence, as there are many small running seams of water. These are very troublesome as they Wash rock chips into the drill hole. It is possible to drill a hole even though there is water in it, but almost impossible to retract the drill steel because of many rock chips on top of the drill bit when air is used.

In drilling sloping holes the rock dust settles to the side or bottom of the hole where the compressed air cannot come in contact with the rock dust to remove it. In drilling sloping holes, rock chunks and particles commonly drop completely in or partially into the hole. When this happens, it is often impossible to extract the drill steel and rock bit because of the binding action of the rock chunks on top of the rock bit. Upon extraction of a rock bit of my design, it will cut these interfering, protruding particles and provide a much cleaner, smoother hole for loading explosives. It is these rock chunks that make extraction difficult in either air or water drill- An object is to provide a reverse-drilling rock bit of improved construction. Reverse cutting or drilling refers to the action that takes place upon extraction of the bit and drill steel. It is still rotating in the same direction except that it is coming out of the hole.

I am aware that others have drill bits also designed to drill in reverse by ready removal. For example, in the Patent No. 2,558,341, issued on June 26, 1951, to Mr. S. L. Cory et :al., titled Auger Rock Drill Bit, finds a solution to this probe which involves the use of drugs. It is the object of my invention to provide the reverse drilling surfaces disposed directly above the radially extending wings of the rock drill bit for more durable construction, for economy of manufacture, and for more efiicient operation.

Another example is the Patent 2,519,861, issued to S. G. Turner on August 22, 1950, titled Double-Acting Drill Bit. However it is an object of my invention to provide greater clearance between the cutting wings of the drill bit for the more efficient removal of rock bits, to provide a lesser surface in contact with the edges of the drill hole to reduce friction, and to provide cutting edges which are sharp rather than sloped for efficiently cutting into the rock and to avoid possibility of the rock slipping off the cutting surface.

Another object is to provide a drill having reverse cutting surfaces constructed so that particles of material that it breaks up, dislodges, and cuts are pushed directly into the path of the air or water that passes between the rates pbifiilii ice radial extending cutting edges for the removal of the material that one is drilling.

It is also an important object to provide a bit having a reverse cutting surface which helps to drill a straight hole as compared with prior art bits of bell shape as it has more supporting surface along the side of the hole. This is important in drilling sloping and folded formations especially when they contain soft and hard spots as in some granite and limestone formations.

With standard rock bits in drilling this type of formation, it is common for the hole to become so crooked that it pinches out the drill steel, in other words, it becomes so far off center that the drill steel can no longer rotate or reciprocate.

A further object is to provide a bit which would be of great value on carbide steel rock bits. These bits are the most expensive and at present it is not practical to use them in some formations where soft shaley material lies between layers of flint or granite or other hard rock, because of the above average loss of drill steel and rock bits in this type of formation.

Other and further objects and advantages of the present invention will be apparent from the following detailed description, drawings and claim, the scope of the invention not being limited to the drawings themselves as the drawings are only for the purpose of illustrating a way in which the principles of this invention can be applied.

Other embodiments of the invention utilizing the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claim.

In the drawings:

FIG. 1 is a side elevation of the reversible drill bit of this invention, shown with a lower portion of the drill steel therein in dotted lines;

FIG. 2 is a top plan view of the dull bit of FIG. 1;

FIG. 3 is a bottom plan view of the drill bit of FIG. 1; and

FIG. 4 is a sectional plan through the drill bit taken on line 44 of FIGURE 1, illustrating the structure of the body of the bit.

In the drawings a reverse drilling rock bit of this invention is generally indicated at 10. It has a cylindrical central portion or body 12 having radial wings or blades 14 protruding outwardly therefrom.

The wings 14 have radial cutting edges 16 on the lower ends thereof, the latter being of substantially V shape, in cross section, as is common in rock bits.

The wings 14 each have a forward side 20 and a rearward side 22 parallel to the forward side with respect to the direction of rotation which is counter-clockwise as seen in FIG. 2.

The Wings 14 each have a lower end 28 protruding farther radially outwardly from the central portion 12 than the respective upper end of the same wing and the outer surface 32 of each wing tapers, converging inwardly from its lower end 28 to its upper end 38.

Substantially all of the forward side 20 of each wing protrudes farther outwardly than the corresponding rearward surface 22, and the outer surface of each Wing tapers inwardly preferably, from its forward lower end to its rearward upper end.

The wings 14 each have upper surfaces 40 which incline downwardly from higher leading ends to lower trailing ends.

It will be seen that many of the taperings and inclinations of the surfaces described provide the drill bit a lesser area in contact with the surfaces of the drill hole than would otherwise be the case, as reduces the friction and increases the efficiency of the drill bit.

It will be further seen that the drill bit as shown is of 3 especially rugged construction, and that it is capable of being manufactured at lesser cost, and otherwise fulfills the objects hereinabove set forth.

The reverse cutting surface 22 is constructed so that particles of material that it breaks up, dislodges, and cuts are pushed directly into the path of the air or water that passes between the radial extending cutting edges 16 and 14 for the removal of the material that one is drilling.

The cutting surface 22 is preferably of carbide steel for durability.

From the foregoing description, it is thought to be Obvious that reverse drilling rock bit constructed in accordance with my invention is particularly well adapted for use, by reason of the convenience and facility with which it may be assembled and operated, and it will also be obvious that my invention is susceptible of some change and modification Without departing from the principles and spirit thereof, and for this reason I do not wish to be understood as limiting myself to the precise arrangement and formation of the several parts herein shown in carrying out my invention in practice, except as claimed.

I claim:

A rock drill bit comprising a substantially cylindrical body having blades with parallel side surfaces extended therefrom, said side surfaces of the blades being spaced from and parallel to radially disposed planes positioned on and extended through the longitudinal axis of said body, the lower ends of said blades being V-shaped in cross section and the vertexes'thereof being positioned on said radially disposed planes through the axis of the body, the peripheral surfaces of the blades at the lower ends thereof being described on a radius from the axis of the body and being inclined inwardly from the points of intersection of the radially disposed planes and peripheral surfaces at the vertexes of the V-shaped lower ends, and said peripheral surfaces of the blades being relieved at points spaced upwardly from said vertexes to the upper end of the body, and the relieved surfaces being in planes tangent to the peripheral surface of the body and tapering inwardly from said points spaced upwardly from said vertexes to the upper end of the body, the lower portions of the peripheral surfaces of the blades being curved outwardly to meet the arcuate peripheral surfaces of the lower ends of the blades.

References Cited in the file of this patent UNITED STATES PATENTS 2,093,045 Hammer Sept. 14, 1937 2,499,282 Roberts Feb. 28, 1950 2,558,341 Cory et a1. June 26, 1951 2,602,639 Green July 8, 1952 

